26
Nov
Pesticide Exposure in Early Childhood Linked to Neurobehavioral Disorders, Study Finds
(Beyond Pesticides, November 26, 2024) A study in Environment International finds that young children who exhibit higher levels of pesticide metabolites in their urine show more pronounced neurobehavioral problems at the age of ten. Researchers in China document how exposure during early childhood, especially during the sensitive window before the age of two, is linked to hyperactivity/inattention problems such as attention deficit hyperactivity disorder (ADHD).
While adding to the body of science connecting pesticide exposure to learning and developmental disorders, this study offers a “novel perspective on characterizing the fluctuation in repeated measurements of multiple environmental chemicals and identifying the potential critical windows,†the authors share. (See previous Daily News coverage here, here, and here.)
The researchers analyze data from questionnaires and urine samples through the ongoing Sheyang Mini Birth Cohort Study (SMBCS), which is a long-term prospective cohort study that associates environmental chemical exposure during pregnancy and childhood to negative health effects. This data addresses combined pesticide exposures in young children with neurobehavior analyses at the age of ten to determine any correlation.
Within the SMBCS, a total of 1303 pregnant women are enrolled. When the children reached ages one, two, three, six, seven, eight, nine, and ten years old, each mother–child pair participated in follow-up visits. During these visits, urine samples were collected and analyzed for pesticide metabolites including pentachlorophenol (PCP), 3,5,6-Trichloro-2-pyridinol (TCPy), and carbofuran phenol (CFP). These represent different classes of pesticides: organochlorines, organophosphates, and carbamates, respectively.
A “Strengths and Difficulties Questionnaire†was utilized that covered “various behavioral domains including emotional symptoms, conduct problems, hyperactivity/inattention, peer relationship problems, and prosocial behavior,†the authors share. They continue, “ADHD symptoms were assessed using the ADHD Criteria of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (ADHD-DSM-IV) rating scale.â€
Complete samples and questionnaires were available for 415 children within SMBCS and are included in this study. In assessing children between ages one to ten, the researchers segmented the data into three phases including infancy and toddlerhood (ages one to two), preschool age (ages three to seven), and early school age (ages eight to ten) to track the periodic changes in trajectories and the stages of children’s growth and development within those phases.
The hyperactivity/inattention scores from questionnaires are significantly positively correlated and showed significant differences among the three childhood phases. The detection rates of the three metabolites (PCP, TCPy, and CFP) in all urine samples collected during the follow-up visits ranged from 95.2% to 100% and were significantly positively correlated in each childhood phase.
The most significantly elevated scores were identified for the group with higher levels of metabolites occurring during infancy and toddlerhood. These results reveal “significant positive associations between pesticide exposure during early life (1∼2 years) and hyperactivity/inattention symptom in 10-year-old children,†the researchers report. They continue, “[I]ndividuals with higher urinary concentrations of the three pesticide metabolites during infancy and toddlerhood (1∼2 years) had elevated hyperactivity/inattention scores compared to those with continuously low exposures (1∼10 years) and those with higher exposure levels during pre-school age (3∼7 years).â€
These results highlight that early childhood, especially before the age of two, represents a critical window regarding neurobehavioral developmental effects of pesticide exposure. This is explained by the combination of children’s weak pesticide metabolism capabilities and high brain plasticity before two years of age. Prior research supports that exposure at a young age, and even during gestation, can cause developmental delays and disorders. (See here, here, here, and here.)
Since children are rapidly growing and developing, they are particularly susceptible to the adverse health effects of pesticides and are disproportionately at risk. “The timing of pesticide exposure is crucial in determining the neurotic damage inflicted, as children’s metabolic function and the growth rates of the nervous system change with age,†the researchers note. “In particular, the period of early childhood is deemed critical for the prefrontal cortex (PFC), implicated in various psychiatric disorders such as ADHD, to establish the foundational neural circuitry essential for higher cognitive functions in later life. Thus, early experiences, including early-life environmental exposure, may shape the trajectories of the PFC and have lasting implications for behavioral regulation throughout life.â€
As the authors state, “Children require more attention in risk assessment than adults due to their unique exposure patterns and special susceptibilities to pesticides, which may occur at different stages of development. They may encounter pesticides through multiple routes, either simultaneously or sequentially. For instance, newborns and infants may ingest pesticides via breast milk contamination. Young children, who often engage in exploratory behaviors, are more prone to accumulating pesticides settled in dust and soil while playing and crawling, leading to increased non-dietary ingestion through frequent hand-to-mouth contact. In addition, children generally breathe more air, drink more water, and consume more food than adults by body weight, resulting in higher doses at the same environment contamination level.”
Chemical exposure at an early age increases the body burden of harmful toxicants, many of which can stay in the body for a lifetime, and escalates the risk for certain diseases such as cancer and Parkinson’s disease. Learn more about the hazards of pesticides for children’s health and how “Children and Pesticides Don’t Mix.â€
With multiple routes of exposure, reducing children’s exposure to harmful chemicals is critical. By adopting organic land management strategies, this exposure can be mitigated. Beyond Pesticides promotes healthy environments for learning and recreation for children. Alternatives are available for schools and for creating sustainable parks that do not unnecessarily put children’s health at risk. Make The Safer Choice to avoid hazardous home, garden, community, and food use pesticides to protect children as they grow and develop.
There are serious long-term health implications for children and youth exposed to the toxic soup of pesticide and chemical residues found in conventionally grown food. Take action to tell your U.S. Representative and Senators to cosponsor S. 5084, which increases the funding available for schools to purchase safe school meals and expands funding for the Organic Certification Cost-Share Program to compensate organic farmers.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source:
Ding, J. et al. (2024) Identifying childhood pesticide exposure trajectories and critical window associated with behavioral problems at 10 years of age: Findings from SMBCS, Environment International. Available at: https://www.sciencedirect.com/science/article/pii/S0160412024006652.
